1. Field Of The Invention
The present invention relates to the field of non-impact keyless chucks used in rotary tools, and particularly, to an improved structure for increasing the operator's grip on the chuck barrel while loosening and tightening the chuck to replace a tool bit carried therein.
2. Prior Art
A variety of keyless chucks are known for use in rotary tools, such as hand-held electric drills, wherein the jaws of the chuck are loosened or tightened by the operator gripping an outer sleeve of the chuck barrel and actuating the motor at low speed to drive the jaws open or closed (see, for example, Von Neudeck U.S Pat. No. 1,705,275). Alternatively, the chuck may be opened or closed by the operator gripping front and rear sleeves of the chuck barrel and rotating these parts in opposite directions (see, for example, Komatsu et al. U.S. Pat. No. 4,695,065).
A disadvantage of both of the foregoing arrangements of chuck actuation is that the operator's ability to control the purchase of the chuck jaws on the tool bit is limited by his ability to grip the chuck barrel. Attempts to overcome this problem led to the development of elastomeric sleeves, such as those described in Cohen U.S. Pat. No. 4,095,811, Sivertson, Jr., U.S. Pat. No. 4,460,296, and Flynn U.S. Pat. No. 4,844,488 which are frictionally secured over the chuck barrel to increase the operator's grip. However, frictionally attached elastomeric sleeves may be subject to several shortcomings, including tearing due to wear and slip between the chuck barrel and the elastomeric sleeve at sufficiently high torque levels. Furthermore, because such sleeves require adequate thickness to maintain their structural integrity, their bulk may interfere with efficient use of the tool in some instances.
Another disadvantage of keyless chucks involves centering the tool bit in the chuck while tightening the jaws, especially for those chuck designs requiring the operator to grip both front and rear chuck sleeves. Elastomeric caps have been described for use at the bit-receiving portion of the chuck barrel for the purposes of gripping the bit (as in Whitehead U.S. Pat. No. 4,575,108) and as a dust guard to keep cuttings out of the chuck mechanism (as in Thessig et al. U.S. Pat. No. 4,664,394). Such elastomeric caps are subject to abrasion against the workpiece, which may significantly reduce their useful lifetimes.
In view of the foregoing, it is an object of the present invention to provide a keyless tool chuck sleeve having an integrally molded elastomeric cover which improves the operator's grip on the chuck barrel for loosening and tightening the jaws of the chuck.
It is another object of the present invention to provide a keyless tool chuck sleeve having an integrally molded elastomeric cover which is not subject to slip at high torque levels.
It is further object of the present invention to provide a keyless tool chuck sleeve having an integrally molded elastomeric cover wherein the elastomeric cover is tear-resistant and will not interfere with normal use of the tool.
It is still another object of the present invention to provide a keyless tool chuck sleeve having an integrally molded elastomeric cover with an abrasion-resistant endcap and which centers tool bits within the jaws of the chuck during opening and closing of the chuck.
It is yet another object of the present invention to provide a keyless tool chuck sleeve having an integrally molded elastomeric cover with an abrasion-resistant endcap and which reduces the quantity of dust and cuttings entering the chuck mechanism.